Sou Uehara visits a Seaside Hospital. He was once hospitalized at this very place. His former companions suffered from an enigmatic disease that killed them off to the point of extinction. Those who survived however, have still not been discharged yet. Sou reminiscences the events that happened “That day”. The disease’s spread to a certain region of a city, the deaths of the adults it lead to, the power of an affected child and furthermore the conclusion of the battle.